Disruption of Blood‐retinal Barrier at the Retinal Pigment Epithelium After Systemic Urea Injection

Abstract

Electron microscopic studies were done on the structural alterations of retinal pigment epithelial cells occurring under osmotic stress utilizing rhesus monkeys and lanthanum nitrate as a tracer. Fluorescein fundus angiography revealed leaking points of fluorescein from the choroid to the retina, and various degenerative alterations of the retinal pigment epithelial cells were observed in these leaking areas. Some cells included many vacuoles in their cytoplasm, but diffusion of lanthanum from the choroid to the outer segment of visual cell was obstructed by the tight junctions between the retinal pigment epithelial cells. Other cells were severely damaged with ruptured membranes. Abundant tracer material diffused through the cytoplasm into the subretinal space. Other cells were broken down in an isolated manner and here marked extravasation of lanthanum into the subretinal space was observed.

The Influence of Hyperosmotic Stress on the Blood‐retinal Barrier Effects on the Electroretinogram

“…The effect of a hyperosmolar solution on the morphology of the RPE has been studied by two groups arriving at somewhat different conclusions. According to Masuyama ( 1976) the tight junctions are opened, while according to Okinami et al (1978) leakage is due to ruptured cell membranes. The reversability observed in our experiments would suggest that the trauma was relatively mild, resulting in partial breakdown of the barrier between the cells rather than a widespread disintergration of cells.…”

Πειραματική Μελέτη Της Διαβατότητας Των Αγγείων Του Αμφιβληστροειδή Και Της Συμπεριφοράς Των Χιτώνων Του Οφθαλμού Ύστερα Από Χορήγηση Εναιωρήματος Κοκκίων Άνθρακα

“…Αυτή η παρατήρηση συμφωνεί με διάφορες θεωρίες που κατά καιρούς είχαν εκφραστεί περί κυστιδιακής μεταφοράς μέσω του ενδοθηλίου (Shea, 1969, Shea, 1973 , Peyman, 1972 (Peyman, 1975, Flage, 1982. Σε αντίθεση, η βλάβη που προκλήθηκε στον αμφιβληστροειδή πιθήκου rhesus μετά την συστηματική έγχυση ουρίας, άφησε τη ζώνη απόφραξης ανέπαφη (Okinami, 1978). Παρατηρήθηκε ότι η διείσδυση του διαλύματος του εναιωρήματος άνθρακα εμφανίζόταν βαθμιαία ίόσο ως προς την εντόπιση όσο και ως προς την ένταση.…”